NMX‑MPMI‑800 / Rev 01 / GUM · 2σ · Inertial Metrology / Noida · India 2026 · Product Page

NMX-MPMI-800 · UNDER CONTRACT — DRDO

Mass properties measuring instrument. Ten parameters, one machine.

Name: Mass Properties Measuring Instrument (MPMI) — CG, MOI & POI
Brand: Neometrix

Mass. Centre of gravity on three axes. Moment of inertia about three axes. Product of inertia in three planes. The MPMI measures all ten inertial parameters of a test article on a single vertical machine — statically on a four-load-cell platform, dynamically as an inverted torsion pendulum on a frictionless air bearing — to GUM-compliant accuracies of ±0.5 mm on CG and ±0.5% on moment of inertia. Under a design-development contract for a DRDO establishment, with foundation, metrology arm, and operator training in scope.

Enquire — inertial metrology Capability sheet (PDF)

Representative render — vertical mass properties measuring instrument: cylindrical machine base with precision rotary table, engraved angle index ring, electronics console and calibration beam with certified test weights in a metrology laboratory

Fig · 01 The instrument — representative render of the type under contract

Parameters

10M · CG · MOI · POI

CG Accuracy

±0.5mm · GUM · 2σ

MOI Accuracy

±0.5% · POI ±2%

Table Capacity

800kg · UUT 25–300 kg

Moment Resolution

<20N·mm · sens. <40

ISO 9001 / 14001 Under contract — a DRDO establishment GeM — Government e-Marketplace GUM-compliant uncertainty · 2σ Noida · India

Overview

Anything that flies obeys its inertia tensor.

Guidance engineers can correct for many things — but not for a centre of gravity nobody measured. Before an aerospace article flies, spins, or separates, its mass properties must be known numbers, not CAD estimates. The MPMI exists to produce those numbers with metrological authority.

Representative render — close-up of a mass properties instrument rotary table: engraved angle index ring with degree scribe lines, threaded fixture-hole grid and pneumatic locking pin block

Fig · 02 The rotary table — angle index ring engraved to the degree, fixture grid, pneumatic anti-rotation lock (representative render)

The instrument is a vertical machine: a precision rotary table on an air-bearing spindle, motor-driven in closed loop to any measurement angle — the operator never positions the table by hand. In static mode, a platform on four load cells resolves the article’s weight into reaction forces and moments: mass and centre of gravity. A portable articulated-arm CMM ties the article’s own coordinate frame to the machine’s, so results are reported in the frame that matters — the article’s.

In dynamic mode the same table becomes an inverted torsion pendulum: the air bearing carries the full weight on a film of air, a torsion rod — clamped and released automatically — provides the restoring spring, and the oscillation period yields moment of inertia with no friction correction at all. Repeat about programmed orientations, apply the parallel-axis theorem, and the machine delivers the article’s full inertia tensor about its own CG.

Ten numbers decide how an article flies. This machine measures all ten — and shows its uncertainty budget for each.

Under Contract · DRDO

Design-development, end to end

Contracted through the Government e-Marketplace by a DRDO establishment for design, development, manufacture and installation — the full engineering cycle, not a catalogue resale, with acceptance by the buyer’s board at site.

Measured · GUM 2σ

Accuracy with an audit trail

Every accuracy is specified to the GUM uncertainty framework at 2σ — mass ≤0.05%, CG ≤±0.5 mm, MOI ≤±0.5%, POI ≤±2% — and proven against a calibration beam and certified standard test weights, not asserted from a datasheet.

Engineered · Air Bearing

Friction is the enemy; remove it

The dynamic measurement floats the article on an air film with negligible friction, so no friction correction contaminates the inertia result — with automatic torsion-rod clamping, remote oscillation initiation, and a moment resolution finer than 20 N·mm.

Architecture

Two modes, one spindle, no hand-cranking.

The diagram below shows both measurement modes as the specification defines them — static for mass and CG, dynamic for the inertia tensor.

FIG · 03MEASUREMENT MODES · STATIC · DYNAMIC

Fig · 03 Static mode — four load cells resolve mass and CG; dynamic mode — inverted torsion pendulum on the air bearing yields the inertia tensor

Arc · 01

The Mainframe

Drive motor, spindle and mounting plate with suspension, force transducers, angle encoder, photoelectric timer and strain gauges in one rigid housing — stiff enough that rotating payloads cannot deflect it into error. An angle index ring engraved to the degree, a pneumatic anti-rotation lock with electrical interlocks for safe loading, and eyebolts for crane handling.

Arc · 02

Static Mode — M + CG

Four load cells under the platform resolve reaction forces and moments into mass and CG. The air bearing indexes the article about the vertical axis for multi-orientation statistics; measuring at 0° and 180° cancels levelling error automatically. Corrections made to the article on-machine appear on the readout instantly — no trial-and-error, no refixturing for the second axis.

Arc · 03

Dynamic Mode — MOI + POI

An inverted torsion pendulum: the air bearing carries article and fixture weight on a friction-free film, the torsion rod clamps automatically — manual chucks are disallowed by specification — and oscillation is initiated from the remote console. Period measurements across programmed orientations build the full inertia tensor, referred to the article’s CG by the parallel-axis theorem.

Arc · 04

Scope of Supply

FPGA-based data acquisition with a remote control console on a 10 m tether, UPS-backed for ≥30 minutes of measurement, compressor and air-dryer set feeding the bearing, vibration-isolation foundation designed and supplied, portable articulated-arm CMM, fixtures, calibration beam and certified test weights — with installation, commissioning, handover and operator training in scope.

Holding a mass-properties, CG or moment-of-inertia measurement tender? Send it across — clause-by-clause compliance matrix within two working days · [email protected]

Send tender spec

Specifications

Reference specification, as contracted.

The parameters below reflect the instrument under contract. Capacity class, envelope, and accuracy targets are re-scoped against your specification.

Full specification — expand

Product	Mass properties measuring instrument (MPMI) · vertical type, rotational axis vertical · design, development, manufacture, installation & training scope
Parameters Measured	Ten on one machine — mass · centre of gravity along 3 axes (Xcg, Ycg, Zcg) · mass moment of inertia about 3 axes (Ixx, Iyy, Izz) · product of inertia in 3 planes (Ixy, Iyz, Izx)
Accuracy (GUM · 2σ)	Mass ≤0.05% · CG ≤±0.5 mm · MOI ≤±0.5% · POI ≤±2% · errors defined per the GUM uncertainty standard
Moment Sensitivity / Resolution	Better than 40 N·mm / better than 20 N·mm
Capacity	Test articles 25–300 kg · up to 800 kg on the rotary table including fixture and interfaces · articles to ~1.7 m envelope
CG / MOI Ranges	CG range 500 mm along the vertical axis · 150 mm horizontal offset · article MOI range 20–60 kg·m²
Static Mode	Horizontal platform on four load cells · reaction forces & moments → mass + CG · air-bearing indexing about the vertical axis · multi-orientation statistical measurement · 0°/180° measurement cancels levelling error · CG on two axes without refixturing · live readout during on-machine correction · results w.r.t. machine and article frames
Dynamic Mode	Inverted torsion pendulum · air bearing carries article + fixture weight (no friction correction) · automatic torsion-rod clamp & release — manual chuck disallowed · oscillation initiated from remote console · orientation series → full inertia tensor · parallel-axis theorem refers results to article CG
Rotary Table	Air-bearing mounting plate · motorised closed-loop positioning to commanded angles — no hand rotation · dial-indication of the article · angle index ring scribed every 1°, numbered every 5°, zero-reference pointer · pneumatic anti-rotation locking pin with electrical interlocks · tare balanced over 360°
Control & DAQ	FPGA-based data acquisition · remote control console on 10 m cable · guided step-by-step software procedure · automatic static→dynamic conversion · automatic scale factors & calibration routine · user-selectable angle reference and sign conventions (password-protected) · results in engineering units with hard-copy printout · no manual calculation required
Utilities & Installation	UPS-backed measurement ≥30 min · compressor + air-dryer set for the air bearing · anchor-bolted to a vibration-isolation foundation (designed & supplied) · eyebolts for crane handling
Metrology Accessories	Portable articulated-arm coordinate measuring machine · fixtures · calibration beam · certified standard test weights
Acceptance	Installation, commissioning and acceptance at the consignee site before the buyer’s board · operator training in scope · 3-year warranty from final acceptance
Status	Under contract — design, development, manufacture & installation for a DRDO establishment via the Government e-Marketplace · configurable to customer specification

PDF · 1 page

Mass Properties Instrument — Capability Sheet

Tender Response

Send your specification — clause-by-clause compliance matrix

Variants

One metrology discipline, sized to your article.

Tenders call this a mass properties measuring instrument, a CG and moment-of-inertia test setup, or an inertial measurement machine. Programmes that specify a spin balance machine use the same CG and product-of-inertia limits this instrument verifies — without spinning the article. The contracted class is one point on a scalable architecture.

Var · 01

The Contracted Class

Articles of 25–300 kg on an 800 kg-capacity air-bearing table, MOI 20–60 kg·m², with foundation, CMM, calibration hardware and training — the configuration now in design-development for a DRDO establishment.

Var · 02

Other Capacity Classes

Lighter benches for sub-25 kg articles and heavier tables beyond 800 kg, longer articles, and extended CG and inertia ranges — the measurement physics scales with the spindle and load-cell class.

Var · 03

Adjacent Metrology

Static-balance and dimensional-metrology stations, fixture engineering for article families, and integration of customer-standard data formats into the measurement software — engineered to the clause.

Var · 04

Facility Scope

Vibration-isolated foundations, environmental integration into existing halls, utilities (clean-air plant, UPS), acceptance-test procedures, documentation regimes, and multi-year support — contracted alongside the instrument.

Applications

Where it serves.

Wherever a wrong centre of gravity is an expensive discovery.

A · 01Satellites & spacecraft — CG and inertia tensors for attitude-control budgets

A · 02Launch-vehicle stages & payloads — verified mass properties before integration

A · 03UAVs & aerial targets — measured CG for stability and autopilot tuning

A · 04Aerospace stores & pods — balance data for carriage and separation analysis

A · 05Precision rotating assemblies — inertia verification for drives and gimbals

A · 06National R&D laboratories — traceable inertial metrology for qualification programmes

FAQ

Common questions.

Plain-language answers from the engineering team.

Q · 01 What exactly are the ten parameters?

One mass; three centre-of-gravity coordinates (Xcg, Ycg, Zcg); three moments of inertia about orthogonal axes (Ixx, Iyy, Izz); and three products of inertia (Ixy, Iyz, Izx), which capture how the mass distribution couples the axes. Together they are the article’s complete rigid-body identity — everything a simulation, autopilot or balance calculation needs. The MPMI measures all ten on one machine, in one setup philosophy, and reports them in the article’s own coordinate frame.

Q · 02 How is the accuracy actually proven?

Not by datasheet. The specification defines every error to the GUM — the international Guide to the Expression of Uncertainty in Measurement — at a 2σ confidence level, and the machine ships with the means of proof: a calibration beam and certified standard test weights that place known masses at known offsets. Measure the standard, compare to certificate, and the uncertainty budget is demonstrated live — at installation and at every recalibration after.

Q · 03 Why an air bearing and a torsion pendulum for inertia?

Because friction is the one error you cannot calibrate away. In dynamic mode the article’s full weight rides on a film of air with negligible friction, so the oscillation is governed by the article’s inertia and the rod’s stiffness — not by stiction — and no friction correction ever enters the result. The torsion rod supplies a pure, repeatable restoring torque; its clamping is automatic (the specification expressly disallows manually clamped chucks); and the measured period converts directly to moment of inertia.

Q · 04 How does the machine know the article’s own coordinate frame?

A portable articulated-arm coordinate measuring machine probes reference features on the article and the machine, establishing the transform between the two frames. From then on every result — CG offsets, inertia axes — is reported both with respect to the instrument and with respect to the article itself, which is the number the designer actually needs. The same arm measures the load-cell reaction distances that the static solution depends on.

Q · 05 What comes with the instrument beyond the machine itself?

The working ecosystem: an FPGA-based data acquisition and remote-control console on a 10 m tether, UPS backing for at least 30 minutes of measurement, the compressor and air-dryer set that feeds the bearing, a vibration-isolation foundation designed and supplied for the site, the articulated-arm CMM, article fixtures, the calibration beam with certified test weights, guided step-by-step software, and operator training — through installation, commissioning and acceptance at site.

Q · 06 Can you build to our specification exactly?

That is the standard engagement. The contracted instrument was bid clause-by-clause on the Government e-Marketplace against a defence R&D establishment’s specification — capacity, accuracies, uncertainty framework, scope — and is in design-development against it. Send yours: article mass and envelope, accuracy targets, foundation constraints, documentation regime. A compliance matrix returns within two working days; export enquiries are handled subject to Government of India authorisation.

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Get a quotation

Send your mass-properties
measurement specification.

The Projects desk replies within two working days with a clause-by-clause compliance matrix and a budgetary quotation. Write to [email protected] or use the form.

Enquire — inertial metrology Capability sheet (PDF) +91 7777 876 876

ISO 9001 / 14001 UNDER CONTRACT — A DRDO ESTABLISHMENT GUM · 2σ · INERTIAL METROLOGY MADE IN NOIDA · INDIA

Mass properties measuring instrument. Ten parameters, one machine.

Anything that flies obeys its inertia tensor.

Design-development, end to end

Accuracy with an audit trail

Friction is the enemy; remove it

Two modes, one spindle, no hand-cranking.

The Mainframe

Static Mode — M + CG

Dynamic Mode — MOI + POI

Scope of Supply

Reference specification, as contracted.

One metrology discipline, sized to your article.

The Contracted Class

Other Capacity Classes

Adjacent Metrology

Facility Scope

Where it serves.

Common questions.

Precision test & measurement from Neometrix.

Inertial Loading Test Facility

Aircraft Tyre Nitrogen Charging Rig

Dry & Oil-Free Compressed Air System

Send your mass-properties
measurement specification.

Similar Products

Share This Page

Mass properties measuring instrument. Ten parameters, one machine.

Anything that flies obeys its inertia tensor.

Design-development, end to end

Accuracy with an audit trail

Friction is the enemy; remove it

Two modes, one spindle, no hand-cranking.

The Mainframe

Static Mode — M + CG

Dynamic Mode — MOI + POI

Scope of Supply

Reference specification, as contracted.

One metrology discipline, sized to your article.

The Contracted Class

Other Capacity Classes

Adjacent Metrology

Facility Scope

Where it serves.

Common questions.

Precision test & measurement from Neometrix.

Inertial Loading Test Facility

Aircraft Tyre Nitrogen Charging Rig

Dry & Oil-Free Compressed Air System

Send your mass-propertiesmeasurement specification.

Similar Products

Share This Page

Send your mass-properties
measurement specification.